Title:
Reliability-Based Assessment of Concrete Strength in Existing Structures
Author(s):
F. M. Bartlett
Publication:
Symposium Paper
Volume:
198
Issue:
Appears on pages(s):
85-102
Keywords:
compressive strength; concrete cores; evaluation; in-place strength;
load; resistance
DOI:
10.14359/9992
Date:
3/1/2001
Abstract:
In 1988, the collapse of a supermarket roof in Burnaby, Canada, highlighted the need to distinguish between the specified strength and the actual strength of a material when evaluating existing structures. It is unsafe to calculate resistances using the actual strength instead of the specified strength in conven-tional resistance equations with customary resistance factors. This is the rationale behind current criteria for the evaluation of existing bridges in Canada, that require in-place strength data to be converted to equivalent specified strengths. In this paper, the statistical relationship between the specified strength and the actual in-place strength of concrete is examined. A method is summarized which enables concrete core compression strength data to be converted to an equivalent specified strength for structural assessment purposes. The method is illustrated by a case study involving 1200 40-year-old precast stringer bridges in Alberta, Canada.